This Blog is dedicated to two channel audio reproduction equipment mostly constructed by me and good music in general.

Tuesday, October 21, 2008

Kit form Phono preamp

The construction for the preamp was reasonably easy once I found the right enclosure. Up to that point I tried a number of different boxes. What I was trying to do was find an enclosure which worked with all of the external connections for the kit mounted on the cct. brd. Once I removed them to mount them off-board things got better. The hard ABS plastic case fitted the cct. brd. easily and once lined with a Al and tar foil provided a good enclosure for the project (also see image above). The gain pot is mounted to the cct. brd. so mounting the brd. is critical to ensure the pot can extend out of the box. Insulated gold plated RCAs were used but probably not required in a plastic case. Non-insulated would have been OK.

Cct. brd. populating is easy from the kit except when fitting components for the various compensations. Though there is information for five different compensations there is only enough parts for one. The RIAA is the logical choice. Also if you install for other compensations you have to be able to access the cct. brd. to link them in.

An AC supply is used to bring energy to the device. +/- 12V regs. are mounted on the brd. and of course a diode assembly. A good size copper shield is mounted between sensitive ccts. and the power section. Some capacitors can be upgraded but others, due to their size cannot be. Often I used silver wire for signal line hook-up but in this case stuck with shielded wire. The preamp is exceptionally quiet and has a very smooth sound.